High altitude, long endurance, unmanned aircraft and methods of operation thereof

ABSTRACT

Embodiments include one or more high altitude, long endurance (HALE) unmanned aircraft capable of persistent station-keeping having one or more electromagnetic (IR/Visual/RF) sensor elements or suites for purposes of survey and/or signal gathering. Embodiments include one or more high altitude, long endurance (HALE) unmanned aircraft capable of persistent station-keeping having a directable laser. Embodiments include a group of four or more high altitude, long endurance (HALE) unmanned aircraft configured as GPS repeaters.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/082,983, filed Mar. 28, 2016, which is a continuation of U.S. patentapplication Ser. No. 13/525,045, filed Jun. 15, 2012, which issued asU.S. Pat. No. 9,404,750 on Aug. 2, 2016, which is a continuation ofInternational Application No. PCT/US2010/061160, filed Dec. 17, 2010,which claims priority to and benefit of: U.S. Provisional PatentApplication Ser. No. 61/288,238, filed Dec. 18, 2009; U.S. ProvisionalPatent Application Ser. No. 61/288,249, filed Dec. 18, 2009; and U.S.Provisional Patent Application Ser. No. 61/288,254, filed Dec. 18, 2009;all of which, including appendixes, are hereby incorporated herein byreference in their entirety for all purposes.

TECHNICAL FIELD

The invention, in its several embodiments, pertains generally toaircraft and their component systems, and more particularly to HighAltitude, Long Endurance (HALE) unmanned aircraft having high altitudestation-keeping capabilities and methods of use of HALE unmannedaircraft.

BACKGROUND

The interaction of space-based communication systems and space-basedsurveillance systems with terrestrial systems and/or low altitudeaircraft may be intentionally degraded by third-party emissions and/oratmospheric effects. For example, a receiver of Global PositioningSystem (GPS) signals receives relatively weak signals from GPSsatellites at known frequencies. Accordingly, the GPS receiver may besubject to signal frequency power jamming by third parties. In addition,the Earth's atmospheric properties limit performance ofterrestrially-based space surveillance telescopes with electro-opticaland infrared, or radar-based, orbital imaging systems used to viewobjects in orbit. As a consequence of atmospheric attenuation, anddifficulty in obtaining diplomatic clearance for basing spacesurveillance systems on foreign soil, the domestic entities may belimited in their options to support space operations from surfacesites—at ground level or at sea level.

Terrestrially-based space systems are typically limited by geographyand/or national boundaries. These Earth-based sites may only seeoverhead orbits when orbital mechanics cooperate with their terrestriallocation. Additionally, Earth-based sites' operations may often befurther constrained by available limited infrastructure and long-leadlogistical support. The lack of space situational awareness fromphysically limited, and potentially restricted, terrestrially-basedspace surveillance systems creates both limitations and vulnerabilitiesfor terrestrial operations that may be highly-dependant on space effectsprovided by orbital systems.

Satellites may employ powerful digital cameras to image areas ofinterest on the Earth's surface. Such cameras use various visible andinfrared sensors behind large optical systems. Their sensors may bedesigned to be sensitive to the amounts of light emanating from the areaof interest of the Earth's surface. Focused intense light of or within asatellite camera-sensitive spectral band may cause flash blindness andprevent the camera from imaging its intended area of interest.Terrestrial-based source of the intense light are challenged by theirphysical location relative to a target satellite camera, and are furtherchallenged by atmospheric attenuation.

DISCLOSURE

Disclosed are exemplary methods for, and system embodiments of aplurality of high altitude, long endurance (HALE) unmanned aircraftaugmenting communication channels, including global positioning system(GPS) signal augmentation, and exemplary methods for, and systemembodiments of a plurality of HALE unmanned aircraft interdictingobservations and/or communications of orbital assets, such assatellites. An exemplary HALE aircraft may loiter at 65,000 feet abovemean sea level (AMSL), within the stratospheric layer of 55,000 to70,000 AMSL, and the atmosphere at 65,000 feet and the density may be7.4% of sea level density. At 65,000 feet there may be only 1.4% as manyair molecules to look through versus at sea level. The rarifiedatmosphere translates to less attenuation of the optics or broadcastedpower when compared to terrestrial sensors. The turning radius of a HALEunmanned aircraft may provide for a relatively stationary airborneposition for communication relay equipment to rebroadcast the embeddedGPS information. An exemplary method of global positioning system (GPS)signal augmentation may comprise: (a) deploying a group of four or morehigh altitude, long endurance (HALE) unmanned aircraft, each unmannedaircraft comprising a GPS antenna, GPS receiver, and a GPS repeater; (b)receiving, by at least four of the four more HALE unmanned aircraft, aGPS signal from a respective GPS satellite; and (c) forming, by each ofthe at least four HALE unmanned aircraft respectively, a repeatablereceived GPS signal for transmission. The exemplary method may furthercomprise transmitting, by each of at least four HALE unmanned aircraft,the respective, repeatable received GPS signal. Optionally, theexemplary method may further comprise transmitting within a definedgeographic boundary, by each of at least four HALE unmanned aircrafts,the repeatable received GPS signal. In addition, the previousembodiments may include the group of four or more HALE unmanned aircrafteach flying in one or more station-keeping patterns in a stratosphericlayer above a first defined terrestrial region. Also, the method mayfurther comprise relocating, by the group of four or more HALE unmannedaircraft, to fly in one or more station-keeping patterns in astratospheric layer above a second defined terrestrial region.

An exemplary system embodiment of global positioning system (GPS) signalaugmentation may comprise a group of four or more high altitude, longendurance (HALE) unmanned aircraft, each aircraft comprising a GPSantenna, GPS receiver, and a GPS repeater; wherein each HALE unmannedaircraft may be configured to receive a GPS signal from a respective GPSsatellite, and form, a repeatable received GPS signal for transmission.In some system embodiment, each of at least four HALE unmanned aircraftmay be further configured to transmit, within a defined geographicboundary, the repeatable received GPS signal. In addition, in someembodiments, each HALE unmanned aircraft, of the group of four or moreHALE aircraft, is configured to fly in one or more station-keepingpatterns in a stratospheric layer above a first defined terrestrialregion. In some system embodiments, each HALE unmanned aircraft, of thegroup of four or more HALE aircrafts, may be configured to relocate andfly in one or more station-keeping patterns in a stratospheric layerabove a second defined terrestrial region. Some of the exemplary systemembodiments may include each HALE unmanned aircraft being configured topersist at an altitude for two or more twenty-four hour periods, andconfigured to land for re-supply and/or repair, i.e., aircraft and/oronboard component repair; and thereafter return to a stratosphericlayer.

Embodiments include communication interdiction and/or passivesurveillance interdiction. For example, a method of satellite sensorinterdiction may comprise: (a) deploying a first high altitude, longendurance (HALE) unmanned aircraft comprising a satellite tracker and adirectable electromagnetic (EM) radiation emitter in cooperation withthe satellite tracker; (b) acquiring, by the satellite tracker, asatellite having an onboard EM sensor; (c) tracking, by the satellitetracker, the acquired satellite; and (d) emitting interdicting EMradiation, by the directable EM radiation emitter, to the trackedsatellite. The exemplary method may further comprise, prior to the stepof emitting by the first HALE unmanned aircraft: (a) deploying a secondHALE unmanned aircraft comprising a satellite tracker; (b) signaling bythe first HALE unmanned aircraft to the second HALE unmanned aircraft,the location of the tracked satellite; (c) acquiring, by the satellitetracker of the second HALE unmanned aircraft, the satellite tracked bythe first HALE unmanned aircraft; and (d) tracking, by the satellitetracker of the second HALE unmanned aircraft, the satellite tracked bythe first HALE unmanned aircraft. The method may further comprise thesecond HALE unmanned aircraft transmitting, by the second HALE unmannedaircraft, an interdiction assessment to the first HALE unmannedaircraft. Optionally, the second HALE unmanned aircraft of the exemplarymethod may further comprise a directable electromagnetic (EM) radiationemitter that is in cooperation with a satellite tracker of the secondHALE unmanned aircraft. The method may further comprise emittinginterdicting EM radiation, by the directable EM radiation emitter of thesecond HALE unmanned aircraft, to the tracked satellite based on aninterdiction assessment of at least one of: the first HALE unmannedaircraft and the second HALE unmanned aircraft. For some embodiments,the directable EM radiation emitter of the first HALE unmanned aircraftof the exemplary method may comprise a turret-mounted laser. In someembodiments, the satellite tracker of the first HALE unmanned aircraftmay comprise a gyroscopically stabilized telescopic platform feeding anelectro-optical sensor in communication with a tracking processor.

System embodiments of satellite sensor interdiction may comprise a firsthigh altitude, long endurance (HALE) unmanned aircraft that comprises asatellite tracker and a directable electromagnetic (EM) radiationemitter in cooperation with the satellite tracker wherein the satellitetracker that may be configured to acquire and track a satellite havingan onboard EM sensor; and where the directable EM radiation emitter maybe configured to emit interdicting EM radiation to the EM sensor of thetracked satellite. The system embodiment may further comprise a secondHALE unmanned aircraft that may comprise a satellite tracker, whereinthe second HALE unmanned aircraft may be configured to receive, viasignaling by the first HALE unmanned aircraft or via signaling via aground station, the location of the tracked satellite; where thesatellite tracker of the second HALE unmanned aircraft may be configuredto acquire the satellite tracked by the first HALE unmanned aircraft;and where the satellite tracker of the second HALE unmanned aircraft maybe further configured to track the satellite tracked by the first HALEunmanned aircraft. The second HALE unmanned aircraft of some systemembodiments may further be configured to transmit an interdictionassessment to the first HALE unmanned aircraft. The second HALE unmannedaircraft of some embodiments may further comprise a directableelectromagnetic (EM) radiation emitter in cooperation with a satellitetracker of the second HALE unmanned aircraft. The directable EMradiation emitter of the second HALE unmanned aircraft of some systemembodiments may be further configured to emit interdicting EM radiationto the tracked satellite based on an interdiction assessment of thefirst HALE unmanned aircraft and/or the second HALE unmanned aircraft.For some system embodiments, the directable EM radiation emitter of thefirst HALE unmanned aircraft of some system embodiments may comprise aturret mounted laser. The satellite tracker of the first HALE unmannedaircraft of some system embodiments may comprise a gyroscopicallystabilized telescopic platform feeding an electro-optical sensor incommunication with a tracking processor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a high altitude, long endurance (HALE) unmanned aircraftinterposed in the stratosphere between a satellite emitter andterrestrial emitters;

FIG. 2 depicts a HALE unmanned aircraft at the equator and its earthwardfield of view;

FIG. 3 depicts a HALE unmanned aircraft configured to track a satelliteand/or interdict a satellite sensor;

FIG. 4 depicts a group of HALE unmanned aircraft interposed in thestratosphere between a satellite emitter and terrestrial emitters;

FIG. 5 depicts two HALE unmanned aircraft relaying communication from aterrestrial RF transmitter and a terrestrial RF receiver;

FIG. 6 depicts a group of HALE unmanned aircraft configured to repeatGPS signals for a terrestrial receiver in the face of an interringterrestrial RF emitter; and

FIG. 7 depicts a member of a group of HALE unmanned aircraft configuredto repeat or augment GPS signals for a terrestrial receiver in the faceof an GPS power jammer.

BEST MODES

FIG. 1 depicts a high altitude, long endurance (HALE) unmanned aircraft110 comprising a fuselage 111 having an outer skin. The fuselage housesa communication suite and may have one or more forward electromagnetic(IR/Visual/RF) sensor suites 112. An electromagnetic radiation sensorarray comprising a plurality of sensor elements 121-126 are depicted asdisposed about the outer skin of the fuselage 111, where the dispositionof the forward sensor element 122 and the tail sensor element 121 definea longitudinal sensor array baseline 131. Also depicted are starboardwingtip sensor element 123 and port wingtip sensor element 124 defininga transverse sensor array baseline 132. Accordingly, the HALE unmannedaircraft is depicted as configured to receive and process signalintelligence from exemplary assets such as a satellite radio frequency(RF) emitter 141, a terrestrial infrared emitter 142, a terrestrialvisual band emitter 143, and a terrestrial RF emitter 144, and the HALEmay do so while flying in a stratospheric layer 150 for a plurality oftwenty-four hours periods.

Sensors may be mounted on top of the HALE aircraft platform, as well as,inside the wings. A HALE aircraft may include wings of substantial spanwhere in such long wings may be largely hollow, and a HALE may include along tail boom. The geometry and distances provided by the HALE aircraftmay make it an ideal near space asset for electromagnetic signalcollection by disposing sensors along and/or at the distal portions ofthe wings and/or tail boom. In addition, the HALE aircraft may remain ataltitude in an almost stationary flight pattern, i.e., from theperspective of a ground observer, over a terrestrial region for days toprovide real-time persistent signal mapping

The receiving and processing of third-party signal emissions, and themapping of the electromagnetic spectrum impinging on the HALE aircraftsensor suite, may be augmented with sensors disposed under the HALEaircraft platform in addition to those sensors disposed on top of theaircraft. In combination with other similarly configured HALE aircraftor other signal collection assets, a thorough understanding of thesignals environment, to include the detection of jamming or analysis orother broadcasts, may be possible to support space and terrestrialoperations. So, just as time-of-arrival analysis may be used betweenwingtip disposed sensors, time-of-arrival or other form of analysis maybe used between sensors disposed across a constellation of similarlyconfigured HALE aircraft.

Space situational awareness, communication signal augmentation, and/orcommunication interdiction may be enhanced by the positioning of one ormore HALE aircraft embodiments. The HALE aircraft embodiments may berepositioned in a constellation of station keeping flight patterns atstratospheric conditions, for example, at 65,000 ft. above sea level,and/or within a range of 55,000-70,000 ft. above sea level, and in someembodiments to 100,000 ft. and thereby provide global persistence over awide area with multiple platforms. At stratospheric conditions, the HALEaircraft embodiments are above weather conditions, and may be largelyinsensitive to day-night variations during an operation. Reference ismade to U.S. Pat. No. 7,281,681, which issued Oct. 16, 2007, toMacCready et al., titled “Hydrogen Powered Aircraft,” and to U.S. Pat.No. 6,913,247, which issued Aug. 16, 2005, to Cox et al., titled“Aircraft Control Method,” both of which are incorporated herein byreference. Reference is also made to U.S. Pat. No. 6,944,450, whichissued Sep. 13, 2005, to Cox, titled “Communication System,” and to U.S.Pat. No. 7,198,225, which issued Apr. 3, 2007, to Lisoski et al., titled“Aircraft Control System,” both of which are incorporated herein byreference. As a stratospheric persistence surveillance platform, a HALEunmanned aircraft may be positioned in geostationary station-keeping,and may be relocated. FIG. 2 depicts a HALE unmanned aircraft (not toscale) over the equator 210 that, by its stratospheric location, cansupport the acquisition of satellites above 100 miles having angles ofinclination less than 17 degrees 220. A HALE aircraft may land torefuel, swap or update equipments, or temporarily stand down forequipment repair, and then be returned to stratospheric station-keeping.A HALE may be redirected to a different geostationary position while ataltitude. A HALE aircraft may comprise substantial wingspan relative tofuselage width, and/or substantial tail boom length relative to fuselagewidth. Accordingly, sensors may be disposed at an outboard position withsufficient separation to support optical three-dimensional view orassessment of the effects of jamming and/or dazzling of satellites bythe instant HALE aircraft or another member of a HALE constellation. Thethree-dimensional viewing may also support identification and assessmentunidentified space assets proximate to friendly space assets. Referenceis made to U.S. Pat. No. 7,802,756, which issued Sep. 28, 2010, toKendall et al., titled “Aircraft Control System,” and to U.S. Pat. No.6,550,717, which issued Apr. 22, 2003 to MacCready et al., titled“Liquid Hydrogen Stratospheric Aircraft,” both of which are incorporatedherein by reference.

Situation awareness may be improved by an operator directing the HALEaircraft over large bodies of water, such as international sea lanes andother ocean areas, where space situational awareness may be achieved viatelescopes and electro-optical and infrared orbital imaging sensors orradar, and associated equipment, integrated on top of and/or into one ormore HALE aircraft platforms. For example, space surveillance in supportof space situational awareness may use electro-optic/infrared (EO/IR)sensors, and/or radar frequency (RF) sensors, mounted on top of a HALEaircraft fuselage. That is, the exemplary sensors may be oriented tolook into space at satellites and space surveillance in support of spacesituational awareness using signal detection equipment mounted on thetop, and/or on the bottom, of a HALE aircraft for electromagneticspectrum mapping or the processing of received third-party signals,e.g., signal intelligence processing. FIG. 3 depicts a HALE unmannedaircraft 110 showing in a cutaway a plurality of lasers 331,332 ofdiffering wavelengths, an optical combiner 333 that feeds the laserlight to a gyroscopically stabilized telescope 335, and the telescopemay be mounted on a two-axis turret 336. FIG. 3 also depicts an EO/IRsensor 337 in cooperation with a tracker processor 338. Accordingly, theHALE unmanned aircraft may observe a satellite 340, and/or blind ordazzle a satellite sensor, and/or jam the communication reception of thesatellite 340.

The space surveillance mission in support of space situational awarenessinvolves surveilling space by looking up into space with sensors from apersistent, i.e., substantially geostationary, HALE aircraft. Anobjective may be to track and understand the friendly asset's order ofbattle and the potentially hostile asset's order of battle—from themoment of launch, for example. Presently available electro-optical,infrared, and radar sensors, looking at Earth, i.e., oriented to receiveinput from Earth, may be detecting against a more cluttered and changingsurface than the orientation of looking up at space presents.Accordingly, exemplary turrets housing sensors may be mounted on aturret of a HALE aircraft, and each turret may be customizable withexisting sensors that allow them to look up against cold space withinfrared, low-light and electro-optical sensors, and see a satellitewith minimal or no distortion by the atmosphere. Accordingly,synthetic-aperture radar (SAR) payloads may comprise the sensor suite ofan exemplary HALE aircraft.

Accordingly, while FIG. 3 depicts a single HALE unmanned aircraft, twoor more HALE unmanned aircraft may be used to jam communicationssatellites where the HALE aircraft may have aimed, or directed, radiofrequency jamming systems emitting into space, and/or using a directedlaser to blind a third-party optical receiver, i.e., to blind or dazzlelow-earth orbit imaging satellites using a HALE aircraft and directedlaser systems emitting into space. A laser or a bank of lasers ofappropriate wavelengths to match that sensitive spectral band or thesatellite sensors, and an optical output power may be mounted within theHALE aircraft platform, e.g., within or proximate to a turret housing.To perform the dazzling or blinding mission, an exemplary HALE aircraftmay be configured with an EO/IR sensor, e.g., the L3-Sonoma 494 orRaytheon MTS-B turret or other radar arrays used in high-performanceterrestrial and aircraft systems. The laser beams from these may becombined by an optical system, the output of which may be fiber opticcoupled to a telescope. Some of the telescope embodiments may be similarto what may be an EO/IR sensor turret modified to project themulti-spectral laser beam toward the target satellite. The telescopesystem may also comprise an imaging sensor that may be used to track thetarget satellite and to assure that the projected laser beam irradiatesthe target. Additional HALE aircraft may be used to provide additionalperspectives from with jamming, including RF jamming via a directed RFpower transmitter, and or dazzling may be effected, and one or moreadditional HALE aircraft may be used to observe the effects on thetarget of the jamming and/or dazzling.

Typically, modern communications satellites carry multiple Ku-bandtransponders employing traveling-wave-tube amplifiers (TWTAs) to providean Effective Isotropic Radiated Power (EIRP) of 50-60 dBW at the edge ofcoverage polygon. Additionally, C-band transponders employing TWTA toprovide an EIRP of 39 dBW at the edge of coverage. Depending on powerand antenna gain, a transmitter that broadcasts a HALE aircraft platformin a near-space altitude of 65,000, within the Equivalent IsotropicRadiated Power (EIRP) of a geostationary communications satellite willinterfere with, or potentially obscure, the signal originating from thesatellite as received by the intended ground station.

Current satellite ephemeris data for a target satellite may be availableand/or data from other sources, such as remote terrestrial stations, mayprovide inter-range vectoring to the HALE aircraft platform,particularly the sensor suite, for target acquisition to determinelocation and orientations for possible EO/IR or radar imaging of asatellite. The tracking sensor on the HALE aircraft platform may beradar or high resolution visual such as HDTV resolution or better in allwavelengths. The HALE aircraft may be on station and the line-of-sight(LOS) between the sensor and the satellite may be within 45 degrees ofnadir.

Exemplary acquisition process: The HALE aircraft platform sensor may bepointed at coordinates calculated from target satellite ephemerisdata—the ephemeris data may resolve to about 1/10th of a degree inazimuth and elevation-well within the capability of the sensor. Oncesighted, the system may engage a video tracking algorithm by pointingthe aperture so as to center the target within the optimal jammingtransmission beam. The system may thereafter point/direct the jammingdevice aperture so as to center the target within the sensor field ofview, track and increase power so as to improve desired jamming. Thesensor may be pointed at coordinates calculated from target satelliteephemeris data because the ephemeris data is typically expected toresolve to about 1/10th of a degree in azimuth and elevation—a valueexpected to be well within the capability of the sensors selected forembodiments. If the target satellite is not within the initial field ofview, the sensor may perform a spiral search scan of the area around theinitial pointing direction until the target is sighted. The sensor suitemay then engage a video tracking algorithm by pointing the turret so asto center the target, i.e. put the curser on target, within the sensorfield of view, e.g., at a middle pixel both horizontal and vertical. Thesensor suite of the turret may then be pointed/directed/oriented so asto maintain the center of the target within the sensor field of view,track and increase zoom or focal length so as to improve trackingaccuracy.

Exemplary sensors may include currently available electro optical andinfrared sensors designed with turret applications such as the RaytheonMTS or Sonoma 494 turrets. Additionally, radar sensors on top of HALEaircraft could include SAR, GMTI or AESA type arrays available toprovide metric and/or imaging data on satellites. These sensors could bemounted on, or integrated into, the HALE aircraft wings or tail boom aswell as the fuselage with associated equipment within the aircraftpayload bays. Sensors such as antennas, arrays, directional algorithmsand equipment currently used on other aircraft or satellites may bemounted on, or integrated into, the HALE aircraft wings or tail boom aswell as the fuselage with associated equipment within the aircraftpayload bays.

A rack of related transmitting equipment, combined with availabletri-band antenna mounted on top of a HALE aircraft provides enough powerand gain to deny, degrade and disrupt a satellite communications signalwith less atmospheric impedance and signal propagation because of theremaining small amount of atmosphere above an orbiting HALE aircraft at65,000 feet, or within a range of 55,000 to 70,000 feet above sea level.

Current satellite ephemeris data for the target satellite may be toprovide inter-range vectoring to the HALE aircraft sensor for targetacquisition. The HALE aircraft may be on station and the line-of-sight(LOS) between the sensor and the satellite may be within the EIRP of theCOMSAT.

As a HALE-mounted laser beam travels farther from its source, itdiverges, and as it diverges, its energy may be spread over a largerarea. In addition, the beam may be attenuated as it passes through whatatmosphere may be present. Once a laser beam reaches the satellitesdetectors, the satellite camera optics gathers all of the light fallingon the objective lens and focuses it onto the surface of the imagesensor. This intensifies the laser irradiance at the surface of thesensor.

Digital image sensors that may be used by orbital targets may includecomplementary metal-oxide semiconductor (CMOS) and charge-coupled device(CCD) sensors, and various arrays or stacks thereof. These sensors havesmall light sensitive areas called pixels, which measure the radiantenergy falling on them. The amount of radiant energy falling on eachpixel may be proportional to the area of the pixel itself. Typical sizesrange from over 20 microns to under 5 microns. For discussion in thisexample a pixel size of 9 microns square may be assumed. So, if there is0.43 mw of laser radiance per sq.cm. at the sensor, and the sensor is 20mm square and the pixels may be 9 microns square then there are 2222pixels across the width and height of the sensor (about 5 megapixels)and there are 0.3496 nanowatts of laser energy falling on each pixel,for example. In other words, the satellite CCD (camera) would beblinded. One may conservatively presume a quantum efficiency of 21% atthe wavelength of the laser radiation. So, for example, a 600 nanometerwavelength (visible red) laser, may be near the peak sensitivity of thered pixels of common CCD sensors. Then we may calculate the energy perphoton as: Ep=h·γ/c, where h is Planck's constant and λ/c is the laserlight frequency from wavelength divided by the speed of light. Solvingfor 600 nm gives 3.3093-19 joules per photon. Therefore, for acontinuous-wave laser source, there would be about 1 trillion photonsper second per pixel. Further assuming a 1 millisecond integration time,which is analogous to shutter or exposure time on a film camera, for aCCD sensor with 21% quantum efficiency, there would be 221,834 electronsof charge on a pixel. Typical CCD sensors saturate at 100,000 electronsper pixel. Therefore, in this example, the satellite camera would beblinded on all red pixels (i.e., exceedingly overexposed).

However, satellite cameras may have sensors covering the full spectrumof visible and several infrared bands. Sensors sensitive in various IRbands have similar plots which peak in their respective bands. To fullyblind a visible CCD sensor it may be necessary to combine the light fromred, green and blue lasers. Reasonable wavelengths would be 450 nm, 530nm and 600 nm, respectively. Additional lasers with appropriate IRwavelength could also be added. Lasers of these wavelengths and in thepower ranges of interest may be existing technology and may beintegrated into a HALE aircraft platform.

The HALE aircraft position accuracy may be determined through a GlobalPositioning Satellite (GPS), and an inertial package, and, if required,star-tracking, where the choice, quantity, and quality of instrumentsmay vary depending on acceptable system signal senescence, and otherperformance parameters. The power and type of jamming may be driven bythe target satellite transponder, channels, signal polarization andtransmitting power in order to ensure targeting and jamming efficiencywith counter-communications equipment integrated into the HALE aircraft.FIG. 4 depicts a group of three HALE unmanned aircraft 411-413, each incommunication with one another, where the group flies in station-keepingpatterns in the stratospheric level, and are collectively within thebeam width of a terrestrial emitter, such as an infrared emitter 421, anvisual band emitter 422, and/or an RF emitter 423. Also depicted in FIG.4 is at least one HALE unmanned aircraft 411 of the group incommunication with a satellite 450. One or more of the terrestrialemitters may be a satellite tracking station using inter-range vectors(IRVs) for observing, and so their transmissions may comprise IRV datathat may be used to support inter-range vectoring.

A HALE aircraft may loiter within its maximum altitude envelope over anarea of interest that may be experiencing GPS jamming. The HALEaircrafts may be configured to operate as an airborne pseudo-satellites(or “pseudolites”) that provide high power GPS signals to overpowerjammers. Accordingly a wing of HALE aircraft, each configured as part ofa pseudolite system may function as a lower-orbiting subset of a GPSsatellite constellation. For example, four pseudolites may be requiredfor a full navigation solution, just like four GPS satellites may berequired today. The exemplary HALE airborne pseudolites may firstdetermine/find each of their own positions from GPS satellites, even inthe presence of jamming. This may be accomplished due to their highaltitude—away from terrestrial-base jammers, and/or via a beam formingantenna and a signal processor that decrease the effects of jamming. TheHALE constellation may then transmit a GPS-like signal (rebroadcast) tothe ground at much higher power and at closer range than the satellitescan accomplish. This signal accordingly overwhelms the jammer and allowsthe multitude of users to overcome the jamming and continue to navigate.

Combining this HALE UAV performance with currently fielded Ku-bandsoftware defined radio systems and associated routers has the directcapability of transmitting several secure links of data ranging from10.71 Mbps to 45 Mbps. 274 Mbps technology may be within a year offielding with the same hardware SWAP as current capability. Similarly,cell phone technology, VHF and other terrestrial support radio, cellphone and other communication systems used by police, fire and othercrisis first responders require contingency capability in the eventterrestrial systems may be inoperable during a crisis. Once compatibleelectronics may be hosted on a HALE aircraft, the platform may act as acommunications relay and broadcast source for first responders as apseudolite platform or cell tower.

A HALE aircraft may be configured to receive and process GPS signalswith or without the aid of an onboard star tracker. Once the GPS signalis received by the one or more radio receivers of the HALE aircraft, thesignals may be translated into the Ku waveform, may be embedded inexisting data communication links, and rebroadcast to receiversintegrated into other platforms, and thus circumventing the GPS-tunedjamming environment without experiencing interference.

Two or more HALE unmanned aircraft may augment or locally replacesatellite communications in the face of jamming and/or disablement ofcommunication satellites. For example, FIG. 5 depicts a first HALEunmanned aircraft 510 positioned, via a station-keeping pattern 511, ataltitude of 55,000-70,000 feet above mean sea level, and within the beamwidth of a terrestrial RF transmitter 520. The first HALE unmannedaircraft 510 is depicted as receiving the transmissions of theterrestrial RF transmitter 520, and relaying or otherwise transmittingthe communications to a second HALE unmanned aircraft 530. The secondHALE unmanned aircraft 530 may be configured to relay the communicationsto additional HALE unmanned aircraft, or, as is depicted in FIG. 5, totransmit the communication to a terrestrial RF receiver 540.

FIG. 6 depicts a group of four HALE unmanned aircraft 611-614 in a setof geostationary flight patterns within the stratospheric layer andwithin the beam width of a terrestrial GPS receiver 620. A terrestrialRF emitter 630 is depicted as interring and/or actively jamming the GPSsignals for the exemplary GPS constellation 640. Augmentation ofprecision navigation and timing of Global Positioning System (GPS)signals received by a HALE-based receiver may be effected by routingsignals through software-defined radios mounted within the fuselage of aHALE aircraft for signal assurance in a jammed environment. Accordingly,augmentation of precision navigation and timing of the GlobalPositioning System signals may be effected by re-broadcasting GPSsatellite RF signal to terrestrial and airborne receivers from GPSrepeater electronics onboard the HALE aircraft. The HALE aircraft may beconfigured with surrogate communications satellite capability, forreconstitution of an airborne communication node, to augment terrestrialcommunication degradation and/or satellite communication (SATCOM) signaldegradation or absence.

FIG. 7 depicts a single HALE unmanned aircraft 710 of a group such as inFIG. 6. The single HALE unmanned aircraft 710 is depicted as including aGPS antenna 711 and GPS receiver 712 for receiving GPS signals from theGPS constellation 750. The single HALE unmanned aircraft 710 is alsodepicted as including a transceiver 713 for transmitting to the groundrepeated GPS signals and/or transmitting to the ground translated GPSsignals in a auxiliary frequency band. If the terrestrial GPS receiver720 may be jammed by a GPS power jammer 760, then the HALE unmannedaircraft 710 may provide a repeater transmission via the GPS frequenciesto the terrestrial GPS receiver 720, or may be configured to transmitthe repeated information via an auxiliary RF channel, e.g., a Ku bandtransmission, to a terrestrial RF receiver 730 in cooperation with theGPS receiver 720. By the transmission of four repeated GPS signals inthe auxiliary RF channel, the GPS receiver, after translation by the RFreceiver 730 processing, may generate a GPS solution.

Precision for surveillance typically depends on accurate location andgeometry, and less so on sensor performance. The position accuracy ofthe HALE aircraft may be determined through an onboard GlobalPositioning Satellite (GPS) receiver and inertial instrument package,and, if required, star-tracking, where the choice, quantity, and qualityof instruments may vary depending on acceptable system signalsenescence, and other performance parameters. In addition, once a HALEaircraft position may be determined in relation to presumably currentsatellite ephemeris data for the target satellite, or for a terrestrialtarget—terrestrial data obtained by surveilling the area of interest, orby other third-party sources, then collection of data may be performedwhere signal and the source of the signals being received may be furtherrefined and pin-pointed.

It is contemplated that various combinations and/or sub-combinations ofthe specific features and aspects of the above embodiments may be madeand still fall within the scope of the invention. Accordingly, it shouldbe understood that various features and aspects of the disclosedembodiments may be combined with or substituted for one another in orderto form varying modes of the disclosed invention. Further it is intendedthat the scope of the present invention herein disclosed by way ofexamples should not be limited by the particular disclosed embodimentsdescribed above.

What is claimed is:
 1. A method of global positioning system (GPS)signal augmentation comprising: deploying a group of two or more highaltitude, long endurance (HALE) unmanned aircraft, each unmannedaircraft comprising a GPS antenna, GPS receiver, and a GPS repeater;receiving, by at least two of the group of two or more HALE unmannedaircraft, a GPS signal from a respective GPS satellite; forming, by eachof the at least two of the group of two or more HALE unmanned aircraftrespectively, a repeatable received GPS signal for transmission;determining communication interdiction by positioning the two or moreHALE unmanned aircraft, wherein a second HALE unmanned aircrafttransmits an interdiction assessment to a first HALE unmanned aircraft;and transmitting, by each of the group of two or more HALE unmannedaircraft respectively, a translated GPS signal in an auxiliary frequencyband for transmission based on the received GPS signal and thedetermined communication interdiction.
 2. The method of claim 1 furthercomprising: transmitting, by each of the at least two of the group oftwo or more HALE unmanned aircraft, the respective, repeatable receivedGPS signal.
 3. The method of claim 2 further comprising: receiving, by aterrestrial GPS receiver, the transmitted GPS signal, wherein aterrestrial radio frequency (RF) emitter is jamming the GPS signal tothe terrestrial GPS receiver from the respective GPS satellite.
 4. Themethod of claim 1 further comprising: transmitting within a definedgeographic boundary, by each of the at least two of the group of two ormore HALE unmanned aircraft, the repeatable received GPS signalassociated with the HALE unmanned aircraft.
 5. The method of claim 1further comprising: flying, by each of the group of two or more HALEunmanned aircraft, in one or more station-keeping patterns in astratospheric layer above a first defined terrestrial region.
 6. Themethod of claim 5 further comprising: relocating, by the group of two ormore HALE unmanned aircraft, to fly in one or more station-keepingpatterns in a stratospheric layer above a second defined terrestrialregion.
 7. The method of claim 1 further comprising: deploying at leastone of the group of two or more HALE unmanned aircraft within a beamwidth of a terrestrial radio frequency (RF) transmitter.
 8. The methodof claim 7 further comprising: receiving, by at least one of the groupof two or more HALE unmanned aircraft deployed within the beam width ofthe terrestrial RF transmitter, an RF signal from the terrestrial RFtransmitter.
 9. The method of claim 8 further comprising: transmitting,by at least one of the group of two or more HALE unmanned aircraft thatreceived the RF signal, the RF signal to another HALE unmanned aircraftof the group of two or more HALE unmanned aircraft; and transmitting, bythe another HALE unmanned aircraft of the group of two or more HALEunmanned aircraft, the RF signal to a terrestrial RF receiver.
 10. Themethod of claim 1 further comprising: transmitting within a definedgeographic boundary, by each of the group of two or more HALE unmannedaircraft, the translated GPS signal in the auxiliary frequency bandassociated with the HALE unmanned aircraft.
 11. The method of claim 10further comprising: receiving, by a terrestrial RF receiver, thetransmitted GPS signal in the auxiliary frequency band.
 12. The methodof claim 11 further comprising: translating, by the terrestrial RFreceiver, the received GPS signal in the auxiliary frequency band to aGPS signal for a terrestrial GPS receiver in communication with theterrestrial RF receiver.
 13. The method of claim 12 wherein aterrestrial RF emitter is jamming the GPS signal to the terrestrial GPSreceiver from the respective GPS satellite.
 14. The method of claim 1wherein the auxiliary frequency band is a Ku band.
 15. The method ofclaim 1 wherein the deployed group of two or more HALE unmanned aircraftare above a first defined terrestrial region, wherein the first definedterrestrial region comprises a terrestrial radio frequency (RF) emitter,and wherein the terrestrial RF emitter is jamming the GPS signal to theterrestrial GPS receiver from the respective GPS satellite within thefirst defined terrestrial region.
 16. The method of claim 15 furthercomprising: transmitting, by each of the group of two or more HALEunmanned aircraft, the respective, repeatable received GPS signal,wherein the transmitted GPS signal overcomes jamming from theterrestrial RF emitter.
 17. The method of claim 16 further comprising:receiving, by a terrestrial GPS receiver, the transmitted GPS signal.18. The method of claim 15 further comprising: forming, by each of thegroup of two or more HALE unmanned aircraft respectively, a translatedGPS signal in an auxiliary frequency band for transmission based on thereceived GPS signal; transmitting within the first defined terrestrialregion, by each of the group of two or more HALE unmanned aircraft, thetranslated GPS signal in the auxiliary frequency band associated withthe HALE unmanned aircraft, wherein the transmitted translated GPSsignal overcomes jamming from the terrestrial RF emitter; receiving, bya terrestrial RF receiver, the transmitted GPS signal in the auxiliaryfrequency band; and translating, by the terrestrial RF receiver, thereceived GPS signal in the auxiliary frequency band to a GPS signal fora terrestrial GPS receiver in communication with the terrestrial RFreceiver.
 19. The method of claim 1, wherein the communicationinterdiction corresponds to a satellite other than the two or more HALEunmanned aircraft.
 20. The method of claim 19 further comprising:jamming communication reception of the satellite based on positioning ofthe two or more HALE unmanned aircraft.